package io.jpress.web.render;


import com.jfinal.kit.LogKit;
import com.jfinal.kit.StrKit;
import com.jfinal.render.FileRender;
import com.jfinal.render.Render;
import com.jfinal.render.RenderException;
import com.jfinal.render.RenderManager;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;

public class RenderImage extends Render {

    protected static final String DEFAULT_CONTENT_TYPE = "image/png";
    protected static String baseDownloadPath;
    protected static ServletContext servletContext;

    protected File file;
    protected String downloadFileName = null;

    public RenderImage(File file) {
        if (file == null) {
            throw new IllegalArgumentException("file can not be null.");
        }
        this.file = file;
    }

    public RenderImage(File file, String downloadFileName) {
        this(file);

        if (StrKit.isBlank(downloadFileName)) {
            throw new IllegalArgumentException("downloadFileName can not be blank.");
        }
        this.downloadFileName = downloadFileName;
    }

    public RenderImage(String fileName) {
        if (StrKit.isBlank(fileName)) {
            throw new IllegalArgumentException("fileName can not be blank.");
        }

        String fullFileName;
        fileName = fileName.trim();
        if (fileName.startsWith("/") || fileName.startsWith("\\")) {
            if (baseDownloadPath.equals("/")) {
                fullFileName = fileName;
            } else {
                fullFileName = baseDownloadPath + fileName;
            }
        } else {
            fullFileName = baseDownloadPath + File.separator + fileName;
        }

        this.file = new File(fullFileName);
    }

    public RenderImage(String fileName, String downloadFileName) {
        this(fileName);

        if (StrKit.isBlank(downloadFileName)) {
            throw new IllegalArgumentException("downloadFileName can not be blank.");
        }
        this.downloadFileName = downloadFileName;
    }

    static void init(String baseDownloadPath, ServletContext servletContext) {
        RenderImage.baseDownloadPath = baseDownloadPath;
        RenderImage.servletContext = servletContext;
    }

    public void render() {
        if (file == null || !file.isFile()) {
            RenderManager.me().getRenderFactory().getErrorRender(404).setContext(request, response).render();
            return ;
        }

        // ---------
        response.setHeader("Accept-Ranges", "bytes");
        String fn = downloadFileName == null ? file.getName() : downloadFileName;
        //response.setHeader("Content-disposition", "attachment; " + encodeFileName(request, fn));
        String contentType = servletContext.getMimeType(file.getName());
        response.setContentType(contentType != null ? contentType : DEFAULT_CONTENT_TYPE);

        // ---------
        if (StrKit.isBlank(request.getHeader("Range"))) {
            normalRender();
        } else {
            rangeRender();
        }
    }

    protected String encodeFileName(String fileName) {
        try {
            // return new String(fileName.getBytes("GBK"), "ISO8859-1");
            return new String(fileName.getBytes(getEncoding()), "ISO8859-1");
        } catch (UnsupportedEncodingException e) {
            return fileName;
        }
    }

    /**
     * 依据浏览器判断编码规则
     */
    public String encodeFileName(HttpServletRequest request, String fileName) {
        String userAgent = request.getHeader("User-Agent");
        try {
            String encodedFileName = URLEncoder.encode(fileName, "UTF8");
            // 如果没有UA，则默认使用IE的方式进行编码
            if (userAgent == null) {
                return "filename=\"" + encodedFileName + "\"";
            }

            userAgent = userAgent.toLowerCase();
            // IE浏览器，只能采用URLEncoder编码
            if (userAgent.indexOf("msie") != -1) {
                return "filename=\"" + encodedFileName + "\"";
            }

            // Opera浏览器只能采用filename*
            if (userAgent.indexOf("opera") != -1) {
                return "filename*=UTF-8''" + encodedFileName;
            }

            // Safari浏览器，只能采用ISO编码的中文输出,Chrome浏览器，只能采用MimeUtility编码或ISO编码的中文输出
            if (userAgent.indexOf("safari") != -1 || userAgent.indexOf("applewebkit") != -1 || userAgent.indexOf("chrome") != -1) {
                return "filename=\"" + new String(fileName.getBytes("UTF-8"), "ISO8859-1") + "\"";
            }

            // FireFox浏览器，可以使用MimeUtility或filename*或ISO编码的中文输出
            if (userAgent.indexOf("mozilla") != -1) {
                return "filename*=UTF-8''" + encodedFileName;
            }

            return "filename=\"" + encodedFileName + "\"";
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
    }

    protected void normalRender() {
        response.setHeader("Content-Length", String.valueOf(file.length()));
        InputStream inputStream = null;
        OutputStream outputStream = null;
        try {
            inputStream = new BufferedInputStream(new FileInputStream(file));
            outputStream = response.getOutputStream();
            byte[] buffer = new byte[1024];
            for (int len = -1; (len = inputStream.read(buffer)) != -1;) {
                outputStream.write(buffer, 0, len);
            }
            outputStream.flush();
            outputStream.close();
        } catch (IOException e) {	// ClientAbortException、EofException 直接或间接继承自 IOException
            String name = e.getClass().getSimpleName();
            if (name.equals("ClientAbortException") || name.equals("EofException")) {
            } else {
                throw new RenderException(e);
            }
        } catch (Exception e) {
            throw new RenderException(e);
        } finally {
            if (inputStream != null)
                try {inputStream.close();} catch (IOException e) {
                    LogKit.error(e.getMessage(), e);}
        }
    }

    protected void rangeRender() {
        Long[] range = {null, null};
        processRange(range);

        String contentLength = String.valueOf(range[1].longValue() - range[0].longValue() + 1);
        response.setHeader("Content-Length", contentLength);
        response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);	// status = 206

        // Content-Range: bytes 0-499/10000
        StringBuilder contentRange = new StringBuilder("bytes ").append(String.valueOf(range[0])).append("-").append(String.valueOf(range[1])).append("/").append(String.valueOf(file.length()));
        response.setHeader("Content-Range", contentRange.toString());

        InputStream inputStream = null;
        OutputStream outputStream = null;
        try {
            long start = range[0];
            long end = range[1];
            inputStream = new BufferedInputStream(new FileInputStream(file));
            if (inputStream.skip(start) != start)
                throw new RuntimeException("File skip error");
            outputStream = response.getOutputStream();
            byte[] buffer = new byte[1024];
            long position = start;
            for (int len; position <= end && (len = inputStream.read(buffer)) != -1;) {
                if (position + len <= end) {
                    outputStream.write(buffer, 0, len);
                    position += len;
                }
                else {
                    for (int i=0; i<len && position <= end; i++) {
                        outputStream.write(buffer[i]);
                        position++;
                    }
                }
            }
            outputStream.flush();
            outputStream.close();
        }
        catch (IOException e) {	// ClientAbortException、EofException 直接或间接继承自 IOException
            String name = e.getClass().getSimpleName();
            if (name.equals("ClientAbortException") || name.equals("EofException")) {
            } else {
                throw new RenderException(e);
            }
        }
        catch (Exception e) {
            throw new RenderException(e);
        }
        finally {
            if (inputStream != null)
                try {inputStream.close();} catch (IOException e) {LogKit.error(e.getMessage(), e);}
        }
    }

    /**
     * Examples of byte-ranges-specifier values (assuming an entity-body of length 10000):
     * The first 500 bytes (byte offsets 0-499, inclusive): bytes=0-499
     * The second 500 bytes (byte offsets 500-999, inclusive): bytes=500-999
     * The final 500 bytes (byte offsets 9500-9999, inclusive): bytes=-500
     * 															Or bytes=9500-
     */
    protected void processRange(Long[] range) {
        String rangeStr = request.getHeader("Range");
        int index = rangeStr.indexOf(',');
        if (index != -1)
            rangeStr = rangeStr.substring(0, index);
        rangeStr = rangeStr.replace("bytes=", "");

        String[] arr = rangeStr.split("-", 2);
        if (arr.length < 2)
            throw new RuntimeException("Range error");

        long fileLength = file.length();
        for (int i=0; i<range.length; i++) {
            if (StrKit.notBlank(arr[i])) {
                range[i] = Long.parseLong(arr[i].trim());
                if (range[i] >= fileLength)
                    range[i] = fileLength - 1;
            }
        }

        // Range format like: 9500-
        if (range[0] != null && range[1] == null) {
            range[1] = fileLength - 1;
        }
        // Range format like: -500
        else if (range[0] == null && range[1] != null) {
            range[0] = fileLength - range[1];
            range[1] = fileLength - 1;
        }

        // check final range
        if (range[0] == null || range[1] == null || range[0].longValue() > range[1].longValue())
            throw new RuntimeException("Range error");
    }
}
